The following information covers the basic requirements and configuration items that must be considered for hosting this service. Specific configuration values will vary from user ot user, so many of these items reflect areas of focus and general guidelines for implementation.
The following items represent the barest minimum of requirements to run this service.
- z/OS 1.12
- REXX
- HLASM 5
- COBOL 4.2
- CICS/TS 4.2
- z/OS Parallel Sysplex (CF for CICS Named Counter Server)
In order to get the most out of this service, we strongly recommend setting up your hosting environment to be elastic and highly-available. This includes:
- Setting up clusters of CICS regions (with multi-tenant hosting)
- Enable WLM-managed Dynamic Sysplex Distribution
- Define Shared Ports for your CICS region clusters
- Employ DNS CNAME records to abstract consumer-view URIs from the DNS A records assigned to the DVIPA
- VSAM RLS for data sharing
Particular configuration values that need to be reviewed and adjusted for your expected usage include the following items. These settings are complementary, and must be considered in unison.
- MAXOPENTCBS - Specified in CICS Resource Definitions, controls the maximum number of open TCBs for threadsafe applications
- MAXSSLTCBS - Specified in CICS Resource Definitions, controls the maximum number of TCBs for SSL and TLS handshake processing
- MAXPROCSYS - Specified in BPXPMRxx, controls the maximum number of processes per system or LPAR
- MAXPROCUSER - Specified in BPXPRMxx, controls the maximum number of processes per user ID, or region ID in this case
- RLS_MaxCFFeatureLevel - In IGDSMSxx, controls the size of data placed in CF cache structures
- RLS_MAX_POOL_SIZE - In IGDSMSxx, limits the size of the RLS local buffer pool
- CF RLS Lock Structure size - Via CFRM policy, general guidance is (10MB * Number of Systems * Lock Entry Size)
- CF RLS Cache Structure Size - Via CFRM policy, general guidance is (RLS_Max_Pool_Size * Number of Systems)
- RLS CF CACHE - In Data Class, controls which VSAM components are eligible for caching
- DFSMS CF Cache Sets - In SMS CDS set up, defines how cache assignments are handled
In addition to the previous settings, these items should be reviewed for applicability:
- LPAR Weighting
- Service Classes
- ASID Weights
- Capacity Planning
- Monitoring
- Coordination with other components (.e.g. DNS changes)
Most of these configuration considerations are covered in a bit more detail in a couple of Redbooks published by IBM in collaboration with the Walmart SMEs. Please refer to these publications for additional information: